Effect of hydroxyl ions on chloride penetration depth measurement using the colorimetric method

In this paper, the effect of hydroxyl ions on chloride penetration depth measurement using the colorimetric method was studied. Equivalent silver nitrate solution (i.e. Ag⁺ = Cl⁻) was added to the NaCl + NaOH solution with different concentrations, then the amount of precipitated silver chloride and silver oxide were determined by chemical methods, and the color of the precipitated products was examined. Results show that the amount of silver chloride formed decreases linearly as OH⁻ to Cl⁻ ratio (r) increases. Thus, the chloride concentration at color change boundary changes with the pH value of the concrete. AgCl has a white color, while Ag₂O has a dark brown color. When the value of r exceeds 4, the color of the mixture looks brown, and color change boundary cannot be easily distinguished.     

沉积型磷块岩的重介质选矿技术

本文以湖北宜昌磷矿为例说明重介质选矿技术在沉积型磷块岩中的应用,研究突破了回收磷块岩单矿物的传统观念,将分选单元扩大到磷块岩集合体条带,从根本上解决了该类型矿石选矿存在细度、温度、药耗高和浮选时间长的难题。半工业性选矿试验采用“重介质 浮选”联合工艺流程,从P_2O_5晶位为23.50％、MgO3.40％的原矿中选得P_2O_5品位为31.19％、MgO1.41％的优质磷精矿,P_2O_5回收率达87.99％。该工艺应用于沉积型磷块岩中既获得精矿又抛弃尾矿在国际上尚属首次,为我国磷矿资源的利用开辟了一条新的途径。     

3D Surface Reconstruction Using a Generalized Distance Function

We define a generalized distance function on an unoriented 3D point set and describe how it may be used to reconstruct a surface approximating these points. This distance function is shown to be a Mahalanobis distance in a higher‐dimensional embedding space of the points, and the resulting reconstruction algorithm a natural extension of the classical Radial Basis Function (RBF) approach. Experimental results show the superiority of our reconstruction algorithm to RBF and other methods in a variety of practical scenarios.     

挖掘机超长臂机加工工艺探讨

超长臂是挖掘机上的重要部件，但是机加工一直是超长臂生产中的难题。分析了超长臂的缮构和机加工特点，针对超长臂质量大、外形尺寸大、机加工精度要求高等特点，深入探讨了挖掘机超长臂的机加工工艺方案，阐述了使用大型数控落地铣镗床和专用机夹具进行超长臂机加工的工艺过程。生产实践证明，该工艺不仅能保证超长臂的机加工质量，还能提高生产效率。     

I Did Not Know Its Prohibited-Academic Dishonesty in Online Courses

There is a disagreement among researchers in regard to academic dishonesty in online as compared to traditional learning settings. Based on this, the aim of the current study was to investigate the connection between academic dishonesty in the virtual versus face-to face teaching/learning settings in relation to students＇ learning motivation, while examining the phenomenon from a cross-cultural perspective. The sample consisted of 1,574 participants-803 from USA and 771 from Israel. The results showed that there are significant differences in students＇ likelihood to engage in academic dishonesty based on the type of course, such that students in face-to-face courses are more likely to engage in acts of academic dishonesty than their counterparts in online courses. In addition, it was found that students＇ propensity to engage in academic dishonesty is explained by motivational orientation, type of course and age. The findings were consistent across student groups in both countries. The phenomenon can be explained by the fact that more intrinsically motivated students self-select online as opposed to traditional classroom courses, and because online instruction facilitates increasing levels of intrinsic motivation.     

基于STC89C52RC的超声波测距系统设计

本文介绍了一种基于STC89C52RC的超声波测距系统的工作原理及其硬件组成和相应的软件流程。硬件系统由脉冲发射电路、接收电路、温度补偿电路和相应的控制电路组成。软件部分采用单片机C语言程序编程,主要由键盘扫描、定时器/计数器初始化、超声波发射子程序、中断服务子程序和LED动态显示子程序构成。同时,为了提高超声波测距精度,采用温度传感器进行环境温度检测,对超声波的传播速度进行校正。实测证明,系统具有较高的测量精度和较强的适应性。     

Cutting force analysis in reaming of ZL102 aluminium cast alloys by PCD reamer

The cutting forces are studied for the reaming of casting aluminium alloy ZL102 (ZAlSi12) using a four-flute PCD reamer on DMG DMU 50 linear five-axis CNC machine. Kistler Dynamometer is used to measure the cutting force (X-, Y- and Z-axes) and torque. Three-coordinate measuring machine is used for measuring cylindricity of machined hole. The cutting force signatures are diagnosed by using Fast Fourier Transform (FFT) algorithm. FFT analysis suggests that fundamental frequency is only determined by cutting speed. The frequency for the thrust signal of cutting force is zero which illustrates that the thrust is constant when cutting speed and cutting feed are fixed. The relationship between the cutting force and cutting parameter are investigated by using FFT filtering. High value of cutting feed and the low cutting speed provide the higher thrust. The optimized machining parameters are provided relative to cutting force (Fx and Fy) and the cylindricity of reamed holes.     

Harnessing data mining to explore incident databases

Large numbers of incident related databases have been established in the last three decades. The majority of attempts to explore these data marts were trials to identify patterns via first glance into the datasets. This study investigated a subset of incidents from fixed facilities in Harris County, TX, extracted from the National Response Center database. By classifying the information into groups and using data mining techniques, interesting patterns of incidents according to characteristics such as type of equipment involved, type of chemical released and causes involved were revealed and further these were used to modify the annual failure probabilities of equipments.     

Incident analysis of Bucheon LPG filling station pool fire and BLEVE

An LPG filling station incident in Korea has been studied. The direct cause of the incident was concluded to be faulty joining of the couplings of the hoses during the butane unloading process from a tank lorry into an underground storage tank. The faulty connection of a hose to the tank lorry resulted in a massive leak of gas followed by catastrophic explosions. The leaking source was verified by calculating the amount of released LPG and by analyzing captured photos recorded by the television news service. Two BLEVEs were also studied.     

数控落地镗铣床在挖掘机超长臂机加工的应用

针对挖掘机超长臂的结构与机加工特点,深入探讨了使用数控落地镗铣床加工超长臂的工艺方案,具体阐述了加工工艺过程。在生产实践中证明数控落地镗铣床不仅能保证超长臂的机加工质量,还能提高生产效率。